Abstract:

An ultra-efficient "green" aircraft propulsor utilizing an augmentor fan
is disclosed. A balanced design is provided combining a fuel efficient
and low-noise high bypass ratio augmentor fan and a low-noise shrouded
high bypass ratio turbofan. Three mass flow streams are utilized to
reduce propulsor specific fuel consumption and increase performance
relative to conventional turbofans. Methods are provided for optimization
of fuel efficiency, power, and noise by varying mass flow ratios of the
three mass flow streams. Methods are also provided for integration of
external propellers into turbofan machinery.

2. The ultra-efficient aircraft propulsor according to claim 1, further
comprising drive means operable to rotationally drive the augmentor fan
by using power from the core engine.

3. The ultra-efficient aircraft propulsor according to claim 1, wherein
the core engine is a combustion engine that has a thermodynamic cycle
comprising at least one of the group consisting of: Brayton, Otto,
Diesel, Rankine, Stirling, Humphrey, Fickett-Jacobs, Wave, Carnot, and a
Hybrid.

5. The ultra-efficient aircraft propulsor according to claim 4, wherein
the thrust reverser means comprises means for changing at least one of
the group consisting of: a pitch orientation of the augmentor fan blades,
fan flow, and core flow.

7. The ultra-efficient aircraft propulsor according to claim 1, wherein
the augmentor fan blades comprise airfoil sections, and wherein a number
of the augmentor fan blades ranges from three to sixty inclusive.

8. The ultra-efficient aircraft propulsor according to claim 1, wherein
the augmentor fan blades comprise blade pitch control means operable to
variably control pitch angles of the augmentor fan blades to provide
desirable augmentor fan blades angles of attack along their span to
enable optimization of an optimization parameter.

9. The ultra-efficient aircraft propulsor according to claim 8, wherein
the optimization parameter is a function of a measure of at least one of
the group consisting of: aerodynamic efficiency, fuel efficiency,
community noise, cabin noise, emissions, takeoff performance, climb
performance, cruise performance, performance in descending flight,
reverse thrust performance, and power division between the augmentor fan,
the ducted fan and the core engine.

10. The ultra-efficient aircraft propulsor according to claim 1, wherein
the augmentor fan blades each have a span ratio ranging from about 0.05
to about 5 to a span of each of the ducted fan blades.

11. The ultra-efficient aircraft propulsor according to claim 1, wherein
the augmentor fan blades each have an average chord to span ratio ranging
from about 0.02 to about 2.

12. The ultra-efficient aircraft propulsor according to claim 1, wherein
an activity factor of the augmentor fan blades is greater than 250.

13. The ultra-efficient aircraft propulsor according to claim 1, wherein a
number of augmentor fan blades and a number of the ducted fan blades are
chosen to avoid sum and difference tones.

14. The ultra-efficient aircraft propulsor according to claim 13, further
comprising:a second augmentor hub ring substantially surrounding an inner
perimeter of the fan cowl and longitudinally spaced from the augmentor
hub ring, and operable to contra-rotate relative to the augmentor hub
ring; anda second augmentor fan driven by the core engine comprising a
plurality of second augmentor fan blades arranged circumferentially
around the second augmentor hub ring, wherein a number of the second
augmentor fan blades is chosen to avoid sum and difference tones.

15. The ultra-efficient aircraft propulsor according to claim 1, wherein
an aerodynamic tip-sweep of a mid chord line of each of the augmentor fan
blades relative to a plane perpendicular to local inflow streamlines is
greater than about 10 degrees and less than or equal to about 60 degrees.

16. The ultra-efficient aircraft propulsor according to claim 1, further
comprising at least a dual load path attachment operable to couple the
augmentor fan blades to the augmentor hub ring.

17. The ultra-efficient aircraft propulsor according to claim 1, wherein a
property of tips of the augmentor fan blades comprises at least one of
the group consisting of: nonzero taper, nonzero sweep, morphably
controllable surfaces, and aerodynamic blowing.

18. The ultra-efficient aircraft propulsor according to claim 1, wherein a
tip of each of the augmentor fan blades is coupled to an augmentor fan
tip ring encircling all of the augmentor fan blades, and wherein the
augmentor fan tip ring is operable to rotate with the augmentor fan.

19. The ultra-efficient aircraft propulsor according to claim 18, further
comprising blade pitch variability operable to allow coupling of the
augmentor fan blades to the augmentor fan tip ring.

21. The ultra-efficient aircraft propulsor according to claim 20, wherein
an average chord of a ring airfoil of the ring airfoil configuration
ranges from 1 to 5 times an average chord of each of the augmentor fan
blades.

22. The ultra-efficient aircraft propulsor according to claim 20, wherein
an average chord of the augmentor fan tip ring ranges from about 0.025 to
about 0.5 of an average chord of the fan cowl.

23. The ultra-efficient aircraft propulsor according to claim 20, wherein
an average thickness to chord ratio of a ring airfoil of the ring airfoil
configuration ranges from about 0.03 to about 0.30.

24. The ultra-efficient aircraft propulsor according to claim 18,
wherein:the augmentor fan tip ring has a slightly noncircular shape when
the augmentor fan is not rotating; androtational loads cause the
augmentor fan tip ring to take a substantially circular shape when the
augmentor fan is rotating at operational rotation speeds.

26. The ultra-efficient aircraft propulsor according to claim 25, wherein
an aerodynamic tip-sweep of a mid chord line of each of the augmentor fan
blades in degrees relative to streamlines is less than or equal to about
60.

27. The ultra-efficient aircraft propulsor according to claim 1, wherein a
preferred activity factor of the augmentor fan blades is at least about
150 and at most about 250.

28. The ultra-efficient aircraft propulsor according to claim 2, wherein
the drive means comprises gear means operable to transmit power
concurrent with changing revolutions per minute.

29. The ultra-efficient aircraft propulsor according to claim 28, wherein
the gear means comprises:at least one driving gear ring;at least one
driven gear ring provided around a periphery of the augmentor hub ring;
anda plurality of connecting gear elements provided between the at least
one driving gear ring and the at least one driven gear ring.

30. The ultra-efficient aircraft propulsor according to claim 29,
wherein:the at least one driving gear ring is provided around the inner
perimeter of the fan cowl; andthe connecting gear elements comprise:a
first gear sprocket engaged by the at least one driving gear ring;a
second gear sprocket engaging the at least one driven gear ring; anda
shaft operable to connect the first gear sprocket and the second gear
sprocket.

31. The ultra-efficient aircraft propulsor according to claim 28, wherein
a circumference of the second gear sprocket is less than a circumference
of the first gear sprocket, to cause an effective gearing wherein
rotational RPM of the driven gear ring is reduced relative to rotational
RPM of the driving gear ring.

33. The ultra-efficient aircraft propulsor according to claim 32, wherein
the propulsor control means further comprises mass flow control means
operable to control at least a fraction of propulsor total mass flow
which is run through the augmentor fan.

34. The ultra-efficient aircraft propulsor according to claim 32, wherein
the propulsor control means further comprises power sharing control means
operable to control at least a fraction of propulsor total power which is
run through the augmentor fan.

35. The ultra-efficient aircraft propulsor according to claim 1, further
comprising flow vectoring means operable to vector a flow downstream of
at least one of the group consisting of: the core engine, the ducted fan,
and the augmentor fan.

36. The ultra-efficient aircraft propulsor according to claim 1, wherein a
diameter of the augmentor hub ring is within about .+-.25% of a diameter
of the ducted fan.

38. The ultra-efficient aircraft propulsor according to claim 37, wherein
the spool core architecture comprises at least one of the group
consisting of: a 1-spool core architecture, a 2-spool core architecture,
a 3-spool core architecture, and a 4 spool core architecture.

39. The ultra-efficient aircraft propulsor according to claim 1, wherein
tips of the augmentor fan blades are substantially located on a circle of
larger size and surrounding an outer perimeter of all of the ducted fan
blades of the ducted fan and an outer perimeter of the fan cowl.

40. The ultra-efficient aircraft propulsor according to claim 39, further
comprising bearing means operable to enable a rotating structural
connection, wherein the augmentor hub ring is structurally coupled by the
bearing means to the fan cowl.

41. The ultra-efficient aircraft propulsor according to claim 39, wherein
a diameter of the augmentor hub ring ranges from about 15% to about 90%
of a diameter of the circle.

42. The ultra-efficient aircraft propulsor according to claim 39, further
comprising drive means comprising gear means operable to rotationally
drive the augmentor fan at lower revolutions per minute than the ducted
fan, using power from the core engine.

43. The ultra-efficient aircraft propulsor according to claim 42, wherein
the gear means is further operable to drive the ducted fan at lower
revolutions per minute than turbine elements of the core engine.

44. The ultra-efficient aircraft propulsor according to claim 1, further
comprising a rotating gear ring operable to provide torque from blade
pitch control unit drives to the augmentor fan blades.

45. The ultra-efficient aircraft propulsor according to claim 1, further
comprising a lobed mixer operable to cool gasses that drive a power
turbine which directly drives the augmentor fan.

46. The ultra-efficient aircraft propulsor according to claim 45, wherein
cooled gasses from the lobed mixer reduces temperature related wear on
the at least one of the augmentor fan blades and at least one blade pitch
control drive.

47. The ultra-efficient aircraft propulsor according to claim 1, wherein
the core engine comprises at least one compressor comprising at least one
of the group consisting of: an axial compressor and a centrifugal
compressor.

49. The ultra-efficient aircraft propulsor according to claim 1, wherein
the augmentor fan blades are twisted from their root ends to their tip
ends.

50. A method for operating an ultra-efficient aircraft propulsor, the
method comprising:providing thrust from a core engine at a first thrust
to total power ratio;providing thrust from a ducted fan at a second
thrust to total power ratio; andproviding thrust from an augmentor fan at
a third thrust to total power ratio.

51. The method according to claim 50, wherein:the third thrust to total
power ratio is greater than the second thrust to total power ratio for a
first set of flight conditions; andthe second thrust to total power ratio
is greater than the third thrust to total power ratio for a second set of
flight conditions.

52. The method according to claim 51, wherein:the first set of flight
conditions comprises takeoff; andthe second set of flight conditions
comprises climb out.

53. The method according to claim 50, further comprising means for setting
the first thrust to total power ratio, the second thrust to total power
ratio, and the third thrust to total power for optimizing takeoff field
length.

54. The method according to claim 50, further comprising providing an
augmentor fan blade hub-to-tip ratio larger than a corresponding ratio
for at least one of a propfan propulsor and a turboprop propulsor.

55. The method according to claim 54, wherein the augmentor fan blade
hub-to-tip ratio is at least about 0.4.

56. The method according to claim 54, wherein the augmentor fan blade
hub-to-tip ratio enables an increased number of augmentor fan blades.

57. The method according to claim 56, wherein the increased number of the
augmentor fan blades minimizes noise by reducing a loading of the
augmentor fan blades.

58. A method for generating thrust for variable cycle engine with an
augmentor fan, the method comprising:providing a first mass flow stream
from an augmentor fan at a first velocity;providing a second mass flow
stream from a ducted turbofan at a second velocity, the second mass flow
stream substantially circumscribed by the first mass flow stream;
andproviding a third mass flow stream from a core engine at a third
velocity, the third mass flow stream substantially circumscribed by the
second mass flow stream.

59. The method according to claim 58, wherein the first velocity is less
than the second velocity and the second velocity is less than the third
velocity.

60. The method according to claim 58, wherein a first difference between
the first velocity and the second velocity reduces at least one of
turbulence and noise generation between the first mass flow stream and
second mass flow stream.

61. The method according to claim 58, wherein a second difference between
the second velocity and the third velocity reduces at least one of
turbulence and noise generation between the second mass flow stream and
third mass flow stream.

Description:

FIELD

[0001]Embodiments of the present disclosure relate generally to turbine
engines, and more particularly relate to augmented turbofan engines.

BACKGROUND

[0002]In the art of commercial airplanes, it is highly desirable to design
airplane and engine configurations that yield reduced fuel burn per
seat-mile, which is a metric of airplane fuel efficiency and carbon
dioxide emissions. Carbon trading and Carbon tax regulations comparable
to those already enacted in the European Union are also likely to be
adopted in other industrialized nations including the United States.
These environmental considerations become even more important in economic
scenarios in which fuel cost increases. This motivates step-change
technologies to reduce fuel consumption per passenger mile.

[0003]This need for reduced fuel burn per seat-mile may be in conjunction
with anticipated near-term increases in stringency of community noise
certification regulations. Current European workplace noise exposure
regulations that affect allowable aircraft cabin noise work together with
local airport environmental policies to also pose significant challenges
to advanced propulsion design. Thus, improvements in community and cabin
noise relative to existing airplanes are also desirable.

[0004]The emissions-based requirements motivate extremely high bypass
ratio engines which can most easily be accomplished with un-shrouded
engines. Some un-shrouded engines however might not have an optimized
configuration for noise reduction. It is also an objective for commercial
airplanes including their propulsors to be perceived in a positive way by
the flying public, similar to how "jet airplanes" with turbofan
propulsors are perceived in a positive way.

[0005]One existing approach to providing improved fuel efficiency or
reduced fuel burn is to utilize turbofan engines with higher bypass
ratios. However, very high bypass ratio turbofans suffer from large
weight and drag penalties associated with their very large fan ducts.
Very high bypass ratio turbofans also suffer from difficulties associated
with achieving under-wing installations in low wing airplanes and
difficulties in achieving simple lightweight thrust reversers.

[0006]Another existing approach to providing improved fuel efficiency or
reduced fuel burn is to utilize a turboprop, propfan, or other "open
rotor" types of propulsor. An open rotor propulsor is effectively a
propeller with a six to ten discrete individual blades exposed at their
tips, with a gas turbine core engine driving the propeller through a
gearbox. Open rotor propulsors provide substantially better fuel burn
through a higher effective bypass ratio and elimination of fan duct drag
and weight, but may have airplane integration challenges, non-optimal
community noise levels, and non-optimal cabin noise and vibration.

[0007]Thus, there is a need for improvements in turbine engine technology
to provide high fuel efficiency, low emissions, low noise, and overall
improved integration.

SUMMARY

[0008]An ultra-efficient "green" aircraft propulsor utilizing an augmentor
fan is disclosed. A balanced design is provided combining a fuel
efficient and low-noise high bypass ratio augmentor fan and a low-noise
turbofan. Three mass flow streams are utilized to reduce propulsor
specific fuel consumption and increase performance relative to
conventional turbofans. Methods are provided for optimization of fuel
efficiency, power, and noise by varying mass flow ratios of the three
mass flow streams. Mass flow may be varied operationally or continuously
to optimize these ratios for take-off, climb, cruise, descent, and the
like. The ability to independently, dynamically, and automatically vary
the power transferred to the airflow between these three mass flow
streams provides an engine with a variable cycle capability. Methods are
also provided for integration of external augmentor fans into turbofan
machinery.

[0010]A second embodiment comprises a method for operating an
ultra-efficient aircraft propulsor. The method comprises providing thrust
from a core engine at a first thrust to total power ratio, and providing
thrust from a ducted fan at a second thrust to total power ratio. The
method further comprises providing thrust from an augmentor fan at a
third thrust to total power ratio.

[0011]A third embodiment comprises a method for generating thrust for a
variable cycle engine with an augmentor fan. The method comprises
providing a first mass flow stream from an augmentor fan at a first
velocity. The method further comprises providing a second mass flow
stream from a ducted turbofan at a second velocity. The second mass flow
stream is substantially circumscribed by the first mass flow stream. The
method also comprises providing a third mass flow stream from a core
engine at a third velocity. The third mass flow stream is substantially
circumscribed by the second mass flow stream.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]Embodiments of the present disclosure are hereinafter described in
conjunction with the following figures, wherein like numerals denote like
elements. The figures are provided for illustration and depict exemplary
embodiments of the disclosure. The figures are provided to facilitate
understanding of the disclosure without limiting the breadth, scope,
scale, or applicability of the disclosure. The drawings are not
necessarily made to scale.

[0013]FIG. 1 is an illustration of a schematic cross sectional view of an
existing ducted turbofan engine.

[0014]FIG. 2 is an illustration of a schematic cross sectional view of an
existing turboprop or single-rotation propfan engine.

[0015]FIG. 3A is an illustration of an exemplary ultra-efficient aircraft
propulsor showing a schematic cross sectional view of a shrouded turbofan
with an unshrouded augmentor fan according to an embodiment of the
disclosure.

[0016]FIG. 3B is an illustration of a rear view of the ultra-efficient
aircraft propulsor of FIG. 3A.

[0017]FIG. 4 is an illustration of a 3-dimensional view of the exemplary
ultra-efficient aircraft propulsor of FIG. 3.

[0018]FIG. 5 is an illustration of two exemplary ultra-efficient aircraft
propulsors mounted on respective wings of a high wing aircraft according
to an embodiment of the disclosure.

[0019]FIG. 6 is a graph illustrating a relationship between a number of
augmentor fan blades, and noise as a function of hub-to-tip ratio for an
exemplary ultra-efficient aircraft propulsor according to an embodiment
of the disclosure.

[0020]FIG. 7 is an illustration of a high angle of attack propeller blade
angle, and a low angle of attack propeller blade angle according to one
or more embodiments of the disclosure.

[0021]FIG. 8 is an illustration of three mass flow streams of an exemplary
ultra-efficient aircraft propulsor according to an embodiment of the
disclosure.

[0022]FIG. 9 is an illustration of velocity profiles for a current art
ducted turbofan, a current art propfan, an exemplary ultra-efficient
aircraft propulsor with an augmentor fan according to an embodiment of
the disclosure, and an "ideal" profile.

[0023]FIG. 10A is an illustration of an exemplary ultra-efficient aircraft
propulsor with a high augmentor fan thrust ratio configuration according
to an embodiment of the disclosure.

[0024]FIG. 10B is an illustration of an exemplary ultra-efficient aircraft
propulsor with a low augmentor fan thrust ratio configuration according
to an embodiment of the disclosure.

[0025]FIG. 11 is a graph illustrating speed vs. percent of runway length
comparing various engine configurations to a propulsor configuration
according to an embodiment of the disclosure.

[0026]FIG. 12 is a graph showing flight Mach number vs. variable augmentor
fan thrust ratio for an exemplary flight envelope according to an
embodiment of the disclosure.

[0027]FIG. 13 is an illustration of an exemplary natural laminar flow on
an engine nacelle for a conventional turbofan.

[0028]FIG. 14 is an illustration of an exemplary extended natural laminar
flow on an engine nacelle of an exemplary ultra-efficient aircraft
propulsor with an augmentor fan according to an embodiment of the
disclosure.

[0029]FIG. 15 is an illustration of a rear view of an augmentor fan
showing an augmentor fan tip ring according to an embodiment of the
disclosure.

[0030]FIG. 16 is an illustration of an exemplary shark fin blade according
to an embodiment of the disclosure in comparison to a conventional
scimitar blade.

[0031]FIG. 17 is an illustration of an exemplary augmentor fan blade pitch
control unit (PCU) mechanism according to an embodiment of the
disclosure.

[0032]FIG. 18 is an illustration of a front view of an exemplary rotating
gear ring of an augmentor fan blade pitch control unit (PCU) according to
an embodiment of the disclosure.

[0033]FIG. 19 is an illustration of an exemplary block diagram for a power
sharing drive system operable to use for power sharing control according
to an embodiment of the disclosure.

[0034]FIG. 20A is an illustration of an exemplary ultra-efficient aircraft
propulsor using a power sharing drive system according to an embodiment
of the disclosure.

[0035]FIG. 20B is an illustration of a cut-away perspective view of the
exemplary ultra-efficient aircraft propulsor using a power sharing drive
system according of FIG. 20A.

[0036]FIG. 21 is an illustration of an exemplary differential gearbox
drive system that can be used as a power splitter according to an
embodiment of the disclosure.

[0037]FIG. 22 is an illustration of an exemplary ultra-efficient aircraft
propulsor showing a single rotor tractor configuration using a power
sharing drive system according to an embodiment of the disclosure.

[0038]FIG. 23 is an illustration of an exemplary ultra-efficient aircraft
propulsor showing a single rotor pusher configuration using a power
sharing drive system according to an embodiment of the disclosure.

[0039]FIG. 24 is an illustration of an exemplary ultra-efficient aircraft
propulsor showing a single rotor tractor configuration with an augmentor
fan in located in front of the turbofan using a power sharing drive
system according to an embodiment of the disclosure.

[0040]FIG. 25 is an illustration of an exemplary ultra-efficient aircraft
propulsor showing a single rotor pusher configuration and a forward
turbofan using a power sharing drive system according to an embodiment of
the disclosure.

[0041]FIG. 26A is an illustration of a perspective view of an exemplary
ultra-efficient aircraft propulsor using a powered augmentor fan hub
rotor according to an embodiment of the disclosure.

[0042]FIG. 26B is an illustration of a schematic cross sectional view of a
portion of an exemplary ultra-efficient aircraft propulsor using a
powered augmentor hub rotor driven by a turbofan according to an
embodiment of the disclosure.

[0043]FIG. 27 is an illustration of an exemplary dual pusher configuration
of an ultra-efficient aircraft propulsor utilizing a lobed mixer to
provide cooled flow to aerodynamically drive an augmentor fan according
to an embodiment of the disclosure.

[0044]FIG. 28 is an illustration of a perspective view of an exemplary
under wing mounting of a dual pusher configuration of an ultra-efficient
aircraft propulsor with an augmentor fan according to an embodiment of
the disclosure.

[0045]FIG. 29 is an illustration of top and side views of an exemplary
tail mounting of a dual pusher configuration of an ultra-efficient
aircraft propulsor with an augmentor fan according to an embodiment of
the disclosure.

[0046]FIG. 30 is an illustration of top, side and front views of an
exemplary tail mounting of a single rotor tractor configuration of an
ultra-efficient aircraft propulsor with an augmentor fan according to an
embodiment of the disclosure.

[0047]FIG. 31 is an illustration of top and side views of an exemplary
tail mounting of a single rotor pusher configuration of an
ultra-efficient aircraft propulsor with an augmentor fan according to an
embodiment of the disclosure.

[0048]FIG. 32 is an illustration of top, side and front views of an
exemplary under wing mounting on an exemplary large mid-wing aircraft of
a single rotor tractor configuration of an ultra-efficient aircraft
propulsor with an augmentor fan according to an embodiment of the
disclosure.

[0049]FIG. 33 is an illustration of side, top and front views of an
exemplary low-wing mounting of a single rotor tractor configuration of an
ultra-efficient aircraft propulsor showing an encircling spinning tip
ring according to an embodiment of the disclosure.

[0050]FIG. 34 is an illustration of a schematic cross sectional view of an
exemplary thrust reverser configuration of an ultra-efficient aircraft
propulsor with an augmentor fan according to an embodiment of the
disclosure.

[0051]FIG. 35 is an illustration of a schematic cross sectional view of an
exemplary ultra-efficient aircraft propulsor with a front mounted
augmentor fan and thrust reverser configuration according to an
embodiment of the disclosure.

[0052]FIG. 36 is an illustration of a schematic cross sectional view of an
exemplary ultra-efficient aircraft propulsor showing a front mounted
augmentor fan according to an embodiment of the disclosure.

[0053]FIG. 37 is an illustration of a schematic cross sectional view of an
exemplary dual puller configuration of an ultra-efficient aircraft
propulsor with an augmentor fan according to an embodiment of the
disclosure.

[0054]FIG. 38 is an illustration of a schematic cross sectional view of an
exemplary dual puller configuration of an ultra-efficient aircraft
propulsor with two augmentor fans according to an embodiment of the
disclosure.

[0055]FIG. 39 is an illustration of an exemplary block diagram of an
ultra-efficient aircraft propulsor engine according to various
embodiments of the disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0056]The following description is presented to enable a person of
ordinary skill in the art to make and use the embodiments of the
disclosure. The following detailed description is exemplary in nature and
is not intended to limit the disclosure or the application and uses of
the embodiments of the disclosure. Descriptions of specific devices,
techniques, and applications are provided only as examples. Modifications
to the examples described herein will be readily apparent to those of
ordinary skill in the art, and the general principles defined herein may
be applied to other examples and applications without departing from the
spirit and scope of the disclosure. Furthermore, there is no intention to
be bound by any expressed or implied theory presented in the preceding
technical field, background, brief summary or the following detailed
description. The present disclosure should be accorded scope consistent
with the claims, and not limited to the examples described and shown
herein.

[0057]Embodiments of the disclosure are described herein in the context of
practical non-limiting applications, namely, aircraft engines and
propulsors. Embodiments of the disclosure, however, are not limited to
such aircraft applications, and the techniques described herein may also
be utilized in other engine and propulsor applications. For example,
embodiments may be applicable to hovercraft or other surface-effect
vehicles, airboats, industrial fan applications, and the like.

[0058]As would be apparent to one of ordinary skill in the art after
reading this description, these are merely examples and the embodiments
of the disclosure are not limited to operating in accordance with these
examples. Other embodiments may be utilized and structural changes may be
made without departing from the scope of the exemplary embodiments of the
present disclosure.

[0059]FIG. 1 is an illustration of a schematic cross sectional view of an
existing ducted turbofan engine 100. The existing ducted turbofan engine
100 may comprise a core engine 102, a ducted fan 104, and a fan cowl 106.
A turbofan is a type of aircraft gas turbine engine that provides
propulsion using a combination of the ducted fan 104 and jet exhaust from
a nozzle of the core engine 102. A first part of an airstream from the
ducted fan 104 passes through the core engine 102 at a high speed,
providing compressed air and oxygen to burn fuel to create power under
the laws of, for example but without limitation, the Brayton
thermodynamic cycle. However, a second part of the airstream bypasses the
core engine 102 at a slower speed than the jet exhaust from the core
engine 102. The slower bypass airstream from the ducted fan 104 produces
thrust more efficiently than the high-speed jet exhaust from the core
engine 102. The more efficient slow speed airstream from the ducted fan
104 reduces specific fuel consumption compared to a pure jet engine with
no ducted fan. This bypass ratio is generally fixed during design and can
be optimal during one phase of flight. Usually, the bypass ratio is
chosen as a compromise between take-off (static thrust), climb, and
cruise.

[0060]Turbofans have a net exhaust speed that is much lower than a pure
turbojet, but faster than a speed of forward flight. Propulsive
efficiency is generally substantially maximized as the mass-average
engine exhaust velocity approaches the speed of forward flight; however,
due to a presence of drag, engine exhaust velocity will be somewhat
higher than the speed of the forward flight. Since turbofans have
subsonic exhaust velocity, they are more efficient than pure turbojets at
subsonic speeds. Jet engines used in currently manufactured commercial
jet aircraft are turbofans due to noise regulations and a need for
reduced fuel consumption, whereas early jet transports like the Boeing
707 and Concorde were turbojets. Turbofans are used commercially mainly
because they are highly efficient and relatively quiet in operation.
Turbofans are also used in many military jet aircraft.

[0061]FIG. 2 is an illustration of a schematic cross sectional view of an
existing turboprop or single-rotation propfan engine 200. The existing
turboprop or single-rotation propfan engine 200 (existing propfan engine
200) comprises a core engine 202, an unducted propeller or unducted
propfan 204, and a fixed ratio reduction gear 206. The existing turboprop
or single-rotation propfan engine 200 is essentially a very high speed
propeller driven by the core engine 202. For flight speeds below about
Mach 0.6 or 0.7 turboprops have historically been more fuel efficient
than either turbojets or turbofans, as they have a higher bypass ratio
and achieve most of their thrust with a flow velocity downstream of the
propeller that has a smaller incremental velocity than the flow
downstream of a ducted fan in a turbofan engine. Propfan versions of the
existing turboprop or single-rotation propfan engine 200 are intended to
have fuel economy close to that of a turboprop but operate at or close to
the speed of the existing turbofan engine 100.

[0062]Propfan powered aircraft generally operate at speeds below about
Mach 0.8. The Mach 0.8 limit is because existing propellers can lose
efficiency at high speed due to limited specific thrust and an effect
known as wave drag that occurs near supersonic speeds. Wave drag can have
a sudden onset, and for the existing propfan engine 200, wave drag effect
can happen any time the unducted propfan 204 is spun fast enough that
blade tips 208 of the existing propfan engine 200 travel near the speed
of sound. Wave drag can occur even if the aircraft is stationary.

[0063]One method of decreasing the wave drag is to sweep the propeller
blades of the unducted propfan 204. Sweeping the propeller blades is an
effective drag reducing feature; however a challenge with existing
propfan designs is that the amount of achievable sweep is structurally
limited due to the propeller blades having to be mounted on small
spinners. Since the base of the propeller blades of the unducted propfan
204 can move more slowly than the blade tips 208, each propeller blade is
progressively more swept toward the blade tips 208, leading to a curved
shape similar to a scimitar. Making propeller blades fatter (e.g. more
like a "fan") by increasing their chord and/or area moves more air and
generates more specific thrust. However, existing propfan designs are
usually mounted on the relatively small spinners, so the chord near the
root has to be small and the root has to be stout resulting in a less
than an optimal aero design.

[0064]The existing propfan engine 200 concept was intended to deliver
better fuel efficiency than the existing turbofan engine 100. In static
and flight tests, versions of the existing propfan engine 200 have
reached an about 30% improvement. This efficiency comes at a price, as
one of the areas that require improvement of the existing propfan engine
200 is noise, particularly in an era where aircraft are required to
comply with increasingly strict noise requirements, such as but without
limitation, to "Stage IV" noise requirements (Department of
Transportation Federal Aviation Administration 14 Code of Federal
Regulations (CFR) Parts 36 and 91 and ICAO Annex 16 Chapter 4
regulations, relevant sections of which are incorporated herein by
reference). Furthermore, it is widely recognized in the industry that the
framework for yet more stringent regulations will be proposed as part of
the ICAO Committee on Aviation Environmental Protection CAEP/8 in year
2010 with discussion between year 2010 and year 2012 with enactment
possibly in year 2015. In the 1980s, many existing propfan engines
configurations such as the exiting propfan engine 200 were tested.
However, projects for the existing propfan engine 200 did not come to
fruition, in part because of excessive cabin noise compared to the
existing turbofan engine 100, and challenges in meeting existing
community noise regulations at the time, (FAR Part 36 Stage 3).

[0065]FIGS. 3A and 3B are illustrations of a schematic cross sectional
view and a rear view of an exemplary ultra-efficient aircraft propulsor
(propulsor 300) respectively showing a shrouded turbofan with an
unshrouded augmentor fan according to an embodiment of the disclosure.
The ultra-efficient aircraft propulsor 300 comprises a core engine 302, a
ducted fan 304, an augmentor fan 306, and a power sharing drive system
312. The augmentor fan 306 is added to the ducted fan 304 and the core
engine 302 to provide three separate and individually controllable mass
flow streams. The ultra-efficient aircraft propulsor 300 may be
structurally coupled to a structural element of the aircraft such as a
wing, an aircraft body, a strut, and the like.

[0066]The core engine 302 is configured to drive the augmentor fan 306.
The core engine 302 may be, for example but without limitation, a
combustion engine substantially utilizing at least one thermodynamic
cycle, such as but without limitation, of a Brayton thermodynamic cycle,
an Otto thermodynamic cycle, a Diesel thermodynamic cycle, a Rankine
thermodynamic cycle, a Stirling thermodynamic cycle, a Humphrey
thermodynamic cycle, a Fickett-Jacobs thermodynamic cycle, a Wave
thermodynamic cycle, a Hybrid thermodynamic cycle, a Carnot thermodynamic
cycle, and the like. The core engine 302 may comprise an air intake at
its forward end and an exhaust at its aft end. The core engine 302 may
also comprise at least one compressor comprising at least one of, for
example but without limitation, an axial compressor and a centrifugal
compressor. The core engine 302 may also comprise at least one combustion
chamber, and at least one of: a low pressure turbine, an intermediate
pressure turbine, and a high pressure turbine. The core engine 302 may
also comprise, for example but without limitation, at least one of a
1-spool, 2-spool, 3-spool, 4-spool core architecture, and the like.
Furthermore, the core engine 302 may be equipped with at least one of a
generator for utilizing power from the core engine 302 as means for
providing electrical power, a bleed port for utilizing power from the
core engine 302 as means for providing pneumatic power, and a pump for
utilizing power from the core engine 302 as means for providing hydraulic
power. In some embodiments, the core engine 302 may comprise an electric
motor.

[0067]The augmentor fan 306 differs from the unducted propfan 204 of the
existing propfan engine 200 in a variety of ways. The augmentor fan 306
comprises an augmentor hub ring 310 and a plurality of augmentor fan
blades 308. The augmentor fan blades 308 are arranged circumferentially
around the augmentor hub ring 310, and the augmentor hub ring 310 is
coupled to a power sharing drive system 312. The augmentor fan 306 may be
coupled to the power sharing drive system 312 by, for example but without
limitation, fixed or rotating struts 318 (5 rotating struts shown) or
other structures. A number of the struts 318 may be the same, more, or
fewer than the number of augmentor fan blades 308. The power sharing
drive system 312 is coupled to and powered by the core engine 302. The
augmentor fan 306 may be controlled by a propulsor controller 316, for
example but without limitation, through actuated pitch control of the
augmentor fan blades 308. An example of an actuated pitch control
mechanism for the actuated pitch control of the augmentor fan blades 308
is explained in more detail in the context of discussion of FIGS. 17-18.

[0068]The augmentor fan blades 308 are coupled to the augmentor hub ring
310, and are driven by the core engine 302. The augmentor fan blades 308
may be coupled to the augmentor hub ring 310 with, for example but
without limitation, a dual load path attachment (not shown). The
augmentor fan blades 308 may comprise airfoil sections. The augmentor fan
blades 308 may be rotated about a hub from their root ends to their tip
ends by the actuated pitch control mechanism which variably controls
blade pitch angles of the augmentor fan blades 308. In this manner,
desirable angles of attack of augmentor fan blades 308 can be provided
along their span to enable optimization of optimization parameters. The
optimization parameters may be defined as a function of, for example but
without limitation, a measure of: aerodynamic efficiency, fuel
efficiency, community noise, cabin noise, emissions, takeoff performance,
climb performance, cruise performance, performance in descending flight,
reverse thrust performance, and power division between the augmentor fan
306, the ducted fan 304, and the core engine 302.

[0069]Outer surfaces of the augmentor hub ring 310 may be substantially
coplanar with adjacent outer surfaces of the fan cowl 314 of the ducted
fan 304. The augmentor hub ring 310 may substantially surround an inner
perimeter of the fan cowl 314. In an alternative embodiment, the
augmentor hub ring 310 may substantially surround an inner perimeter of
an exhaust nozzle of the core engine 302. In one embodiment, the
augmentor hub ring 310 is substantially located on a circle of larger
size and surrounding an inner perimeter of at least one fan cowl 314.
Mounting the augmentor fan blades 308 on the augmentor hub ring 310
allows for a significantly larger number of the augmentor fan blades 308
(e.g., inclusive of 16 blades or more) than the existing propfan engine
200 which may be generally limited to about ten blades. In this manner,
the ultra-efficient aircraft propulsor 300 creates a blade count which
enables reduced loading per blade and thereby serves as means for
reducing blade-loading drive noise. Due to the inherently greater hub
diameter of the augmentor hub ring 310, the augmentor fan blades 308 can
have a greater degree of aerodynamic and acoustic tailoring than the
existing art such as, for example but without limitation, mid-span sweep.
The acoustic tailoring of the augmentor fan blades 308 is explained in
more detail in the context of discussion of FIG. 16 below.

[0070]The power sharing drive system 312 is configured to rotationally
drive the augmentor fan 306 using power from turbine elements in the core
engine 302. The power sharing drive system 312 may also be configured to
rotationally drive the augmentor fan 306 using power from the ducted fan
304. The power sharing drive system 312 may drive the augmentor fan 306
at lower revolutions per minute (RPM) than the core engine 302 and/or the
ducted fan 304. The power sharing drive system 312 may also drive the
ducted fan 304 at lower RPM than turbine elements of the core engine 302.
The power sharing drive system 312 may comprise gears for transmitting
power while changing RPM. The gears may comprise a driving differential
gear from one or more power shafts from the core engine 302. The power
sharing drive system 312 may also comprise a driven gear ring or hub gear
around an inner periphery of the augmentor hub ring 310, and connecting
gear elements between the driving gear ring and the driven gear ring. The
driving differential gear allows a relative thrust of the augmentor fan
306, the ducted fan 304, and the core engine 302 to be changed. The power
sharing drive system 312 is discussed in more detail below in the context
of discussion of FIGS. 19-27 below.

[0071]The propulsor controller 316 may be configured to control at least a
fraction of the propulsor 300 total mass flow which is run through the
augmentor fan 306. The propulsor controller 316 may be further configured
for power sharing control as explained in more detail below. The power
sharing control allows optimization of minimum fuel burn, minimum
operational cost, minimum emissions and/or minimum noise as explained
below. The propulsor controller 316 may also control, for example but
without limitation, at least one of core engine power, core engine
thrust, core engine RPM, core engine fuel flow, core engine critical
temperature parameter, fan thrust, fan RPM, augmentor fan blade pitches,
augmentor fan thrust, augmentor fan RPM, and the like.

[0072]FIG. 4 is an illustration of an exemplary ultra-efficient aircraft
propulsor 400, which is a 3-dimensional rendering of the ultra-efficient
aircraft propulsor 300 of FIG. 3. The ultra-efficient aircraft propulsor
400 comprises a core engine 402, a ducted fan 404, an augmentor hub ring
408, a plurality of augmentor fan blades 406, and a plurality of ducted
fan blades 420. The augmentor hub ring 408 may be substantially aero
dynamically flush with a fan cowl (duct) 410 of the ducted fan 404. A
diameter of the ducted fan 404 may be, for example but without
limitation, about 6 feet to about 12 feet depending on a required thrust.
A number of the augmentor fan blades 406 may be, for example but without
limitation, between three and sixty to reduce noise as explained in more
detail below. The augmentor fan blade span 412 of augmentor fan blades
406 each may be, for example but without limitation, between about 0.05
and about 5 of a ducted fan blade span 414 of each of the ducted fan
blades 420. Each of the augmentor fan blades 406 may have an average
chord 416 to augmentor fan blade span 412 ratio of, for example but
without limitation, between about 0.02 and about 2. Each of tips 418 of
each of the augmentor fan blades 406 may have, for example but without
limitation, nonzero taper, nonzero sweep, morphably controllable
surfaces, aerodynamic suction or blowing, and the like. In one
embodiment, a preferred activity factor of the augmentor fan blades 406
may be at least 150 and at most 250. Alternatively, a preferred activity
factor may be greater than 250. In one embodiment, the tips 418 of the
augmentor fan blades 406 may be substantially located on a circle of
larger size and surrounding an outer perimeter of all of the ducted fan
blades 420 of the ducted fan 404 and an outer perimeter of the fan cowl
410. According to embodiments of the disclosure, the number of the
augmentor fan blades 406 and a number of the ducted fan blades 420 can be
chosen to avoid sum and difference tones. For example, a ratio of
augmentor fan blades 406 to the ducted fan blades 420 may be, for example
but without limitation, 16/13, 16/7, 13/18, and the like.

[0073]The ultra-efficient aircraft propulsor 400 may also comprises
bearing means operable to enable a rotating structural connection,
wherein the augmentor hub ring 408 is structurally coupled by the bearing
means to the fan cowl 410. The bearing means may comprise a variety of
bearing types.

[0074]The ultra-efficient aircraft propulsor 400 comprises a
single-rotation augmentor fan blades 406 located aft of the ducted fan
404. Various embodiments may have the augmentor fan blades 406 turning in
the opposite or same direction as the ducted fan 404, and may have
same-handed or opposite-handed propulsors installed on the port and
starboard sides of an aircraft respectively (e.g., installed on port and
starboard wings). Designs may be optimized to minimize swirl losses
behind a propulsor, and designs may use opposite-handed propulsors to
minimize aircraft net drag and to significantly reduce or eliminate any
necessity to have airframe left and right handed differences to address
aerodynamic asymmetries, for example, due to propulsor swirl effects.

[0075]FIG. 5 is an illustration of two exemplary ultra-efficient aircraft
propulsors mounted on respective wings of a high wing aircraft 500
according to an embodiment of the disclosure. The high wing aircraft 500
comprises, for example but without limitation, two ultra-efficient
aircraft propulsor engines 504. A high wing mounting embodiment shown in
FIG. 5 is one example and other mountings, such as but without
limitation, low wing mountings, body mountings, strut mountings, tail
mountings, a combination thereof, and the like may also be used. Each of
the ultra-efficient aircraft propulsor engines 504 may comprises, for
example but without limitation, 16 augmentor fan blades (e.g., augmentor
fan blades 406 in FIG. 4).

[0076]When conventional aircraft operate on flight patterns over populated
areas, noise requirements often require a pilot to throttle the engine
back. This may not be optimal for certain aircraft operations since a
throttled-back engine can be slower to reach full power, when faster time
to reach full power may be desired for certain flight conditions. This is
particularly so during takeoff, when shortly after rotation during
takeoff, the pilot may have to reduce thrust to reduce noise over
populated areas or noise sensitive locations such as hospitals or schools
which can reduce ride comfort, and increase a length of time and distance
it takes for the aircraft to reach its final efficient cruising altitude.
In contrast, the ultra-efficient aircraft propulsor engines 504 can
function differently by instead changing configuration/thrust ratio over
the populated areas to reduce noise while maintaining power, thereby
maintaining or increasing safety margins and performance. Such an engine
that operates in various modes can be called a variable cycle engine.

[0077]FIG. 6 is a graph 600 showing a relationship between a number of
augmentor fan blades and noise as a function of hub-to-tip ratio for an
exemplary ultra-efficient aircraft propulsor according to an embodiment
of the disclosure. As shown in FIG. 6, noise decreases as the number of
augmentor fan blades increases.

[0078]Existing propeller design practice is generally limited to up to
about six to ten blades because of challenges with, for example but
without limitation, integration of the propeller pitch control unit
(PCU), blade support bearings, blade root size limitations, and the like.
Blade root size for existing propellers is constrained by a small size of
a propeller hub relative to a length of a propeller blade (i.e., low hub
to tip ratio). For the existing propfan engine 200, a forward speed of an
attached aircraft combined with the rotational speed of blades of the
unducted propfan 204 may result in undesirable additional wave drag at
aircraft speeds over about Mach 0.7. Current art cannot use propeller
blades with aggressive tailoring such as an aggressive sweep and lean
(good for low noise) due to flutter caused in part by a small base of
hubs of the current art.

[0079]There are a number of benefits to the large number of blades made
possible with the augmentor fan according to various embodiments of the
disclosure. For example, wave drag can be reduced by using the larger
number of the augmentor fan blades 406 allowing production of more power
at a lower rotational speed. Also, a noise frequency may be changed to a
more desirable frequency.

[0080]A blade pass frequency (BPF) of a fan refers to a frequency at which
blades pass a fixed eternal location. The BPF also indicates a frequency
of noise caused by the blades, since blade noise generally corresponds in
frequency with the BPF. The fan BPF noise level intensity can vary with
the number of blades and the rotation speed. The fan BPF noise level can
be expressed as

B P F = n * t 60 , ##EQU00001##

[0081]where BPF is Blade Pass Frequency in Hz, n is rotation velocity in
rpm, t is number of the blades, and 60 is time in seconds.

[0082]For example, if a fan with 10 blades rotates with 2400 rpm, the BPF
can be calculated as follow:

B P F = ( 2400 r p m )
* ( 10 ) 60 s minute = 400 Hz ##EQU00002##

[0083]The BPF of the existing art is generally below 100 Hz, and for the
existing propfan engine 200, it may be between about 70 Hz and about 100
Hz. For the existing propfan engine 200, the energy in the sound waves
below 100 Hz may be high and audible to the surroundings, especially with
fans with few blades. In contrast, a BPF of embodiments of the present
disclosure can be between about 300 Hz to about 400 Hz due to higher
numbers of blades. Sound waves of 300 Hz to 400 Hz are more readily
attenuated by the atmosphere than 100 Hz sound waves. Sound waves of 300
Hz to 400 Hz also possess more desirable structural resonance excitation
properties relative to 100 Hz or less sound waves. Sound waves of 300 Hz
to 400 Hz enable use of more effective and lighter weight cabin noise
attenuation structures and techniques.

[0084]In an active control of tonal noise from fans, one factor that can
limit an achievable attenuation is fluctuation of the BPF in time. Large
fluctuations in a short time can hinder an algorithm from converging to
the optimal solution, and can require larger actuation systems that
require greater energy. Some fans have less steady speeds than others,
which can be due to unsteady driving mechanisms or the physical structure
of the fan. Environmental effects, such as back pressure and unsteady
blade loading, can also cause speed of the fan to fluctuate. The shifting
in the BPF can be measured using a zero-crossing technique to track the
frequency of each cycle. The controller 316 may be used to control the
frequency of each cycle.

[0085]Also as shown in FIG. 6, noise decreases as hub-to-tip ratio
increases. A high hub-to-tip ratio enables integration of more propeller
blades (e.g., augmentor fan blades 406), which is significantly
beneficial for reducing noise. As mentioned above, the number of the
augmentor fan blades 406 and a number of the ducted fan blades 420 can be
chosen to avoid sum and difference tones. The high hub-to-tip ratio of
the present embodiments allows a single hub blade count of up to 14, 16
or more. This in turn allows greater volume for blade retention, blade
pitch change, and the like. In addition, the high hub-to-tip ratio
enables use of higher activity factor blades with more aggressive
tailoring of the propeller blade shape for low noise and improved
performance at higher speeds. Furthermore, due to high hub diameter, an
overall span (e.g., augmentor fan blade span 412 in FIG. 4) of a
propeller blade can be reduced relieving flutter. A high hub-to-tip ratio
by itself can cause a second order effect that reduces noise. In an
embodiment, an augmentor fan blade hub-to-tip ratio is larger than a
corresponding ratio for at least one of a propfan propulsor and a
turboprop propulsor. The augmentor fan blade hub-to-tip ratio may be, for
example but without limitation, at least about 0.4.

[0086]FIG. 7 is an illustration of a high angle of attack propeller blade
704 and a low angle of attack propeller blade 706 according to one or
more embodiments of the disclosure. Changing an angle of attack of each
of the augmentor fan blades 308 allows the ultra-efficient aircraft
propulsor 300 to vary a percentage of thrust coming from the augmentor
fan 306. The high angle of attack propeller blade 704 can produce more
power, but may also produce more noise. The high angle of attack
propeller blade 704 corresponds to a high augmentor fan ratio as a
percentage of total engine power. The low angle of attack propeller blade
706 can produce less noise, but may also produce less power. The low
angle of attack propeller blade 706 corresponds to a low augmentor fan
ratio as a percentage of total engine power.

[0087]FIG. 8 is an illustration of three mass flow streams 800 of the
exemplary ultra-efficient aircraft propulsor 300 according to an
embodiment of the disclosure. The three mass flow streams 800 comprise a
core mass flow stream 802, a ducted fan mass flow stream 804, and an
augmentor fan mass flow stream 806.

[0088]The core engine 302 (FIG. 3) produces the core mass flow stream 802
with a relative high velocity (Vc). For example but without
limitation, about 10% to about 20% of the thrust from the ultra-efficient
aircraft propulsor 300 may come from the core mass flow stream 802.
Control of the core mass flow stream 802 is provided by throttling the
core engine 302. The core mass flow stream 802 may be substantially
circumscribed by the ducted fan mass flow stream 804.

[0089]The ducted fan 304 produces the ducted fan mass flow stream 804 with
a relative medium velocity (Vd). For example but without limitation,
about 10% to about 50% of the thrust from the ultra-efficient aircraft
propulsor 300 may come from the ducted fan mass flow stream 804. A
difference between Vd and the Vc can reduce at least one of
turbulence and noise generation between the ducted fan mass flow stream
804 and the core mass flow stream 802. Control of the ducted fan mass
flow stream 804 is provided by throttling the core engine 302, or by a
power splitting mechanism such as power sharing drive system 312, which
splits power between the ducted fan 304 and the augmentor fan 306. The
ducted fan mass flow stream 804 may be substantially circumscribed by the
augmentor fan mass flow stream 806.

[0090]The augmentor fan 306 produces the augmentor fan mass flow stream
806 with a relative medium velocity (Vaf), which may be lower than
the velocity (Vd) of the ducted fan mass flow stream 804. For
example but without limitation, about 30% to about 80% of the thrust from
the ultra-efficient aircraft propulsor 300 may come from the augmentor
fan mass flow stream 806. A difference between the Vaf and the
Vd can reduce at least one of turbulence and noise generation
between the augmentor fan mass flow stream 806 and the ducted fan mass
flow stream 804. Control of the augmentor fan mass flow stream 806 is
provided by a power splitting mechanism such as the power sharing drive
system 312, which splits power between the ducted fan 304 and the
augmentor fan 306, or by changing a pitch angle of the augmentor fan
blades 308 of the augmentor fan 306.

[0091]The three mass flow streams 800 of the ultra-efficient aircraft
propulsor 300 may be suitably controlled to vary power and noise output
based on, for example but without limitation, various fight conditions,
operation requirements and parameters, and the like, which can be
programmed into flight control computer logic so that operation is
transparent to a human pilot.

[0092]FIG. 9 is an illustration of velocity profiles for a current art
ducted turbofan 910, a current art propfan 920, an exemplary embodiment
of an ultra-efficient aircraft propulsor with an augmentor fan 930 of the
present disclosure, and an ideal profile 940. In flight, aircraft engines
produce thrust in equivalence to aircraft drag to maintain a steady air
speed. An efficiency difference between engine technologies is in how
much energy is "wasted" producing jet velocity in excess of what is
required to move a given quantity (mass flow) of air to the speed which
produces thrust equal to drag. Thrust from an aircraft is most efficient
when the difference between the thrust for engine and the free stream air
surrounding the aircraft is a minimum. Thus for highest efficiency, a
Delta between an ideal efficiency stream 942 to a free stream 902 (e.g.,
ambient air) is substantially at a minimum. The Delta may be represented
by a mean velocity profile 948 (e.g., 948 for the "ideal" profile 940).
Due to having discrete annular airstreams, there can be some degree of a
step or bell-curve like profile as opposed to an "ideal" mean velocity
profile 948.

[0093]For the current art ducted turbofan 910, the high velocity of the
core engine stream 912 has a large velocity difference relative to a fan
stream 914 as represented by the velocity profile 918. In turn, the fan
stream 914 has a large velocity difference relative to the free stream
902 as represented by the velocity profile 918.

[0094]For the current art propfan 920, the velocity of the propeller
stream 924 has a relatively moderate velocity difference relative to the
free stream 902 as represented by the mean velocity profile 928. However,
the core engine stream 922 has a large velocity difference relative to
the propeller stream 924 as represented by the mean velocity profile 928.

[0095]For the ultra-efficient aircraft propulsor with an augmentor fan 930
use of three streams rather than two moves the mean velocity profile 938
closer to the "ideal" mean velocity profile 948. The velocity of the
augmentor fan stream 936 has a relatively small velocity difference
relative to the free stream 902 as represented by the mean velocity
profile 938 due to the relatively low velocity of the augmentor fan
stream 936. The fan stream 934 has a relatively small velocity difference
relative to the augmentor fan stream 936 as represented by the mean
velocity profile 938. Furthermore, the core engine stream 932 has a
relatively small velocity difference relative to the fan stream 934 as
represented by the mean velocity profile 938 due to removal of
substantially most of the power to the augmentor fan stream 936.
Furthermore, power sharing according to various embodiments of the
disclosure tailors energy in each of the three streams 932/934/936 to
substantially maximize efficiency over various flight regimes, such as
but without limitation, takeoff, climb, cruise, and the like. In this
manner, energy extraction from the core engine stream 932 is
substantially maximized.

[0096]FIGS. 10A and 10B are illustrations of an exemplary ultra-efficient
aircraft propulsor 1000 (propulsor 1000) with a high augmentor fan ratio
configuration, and an exemplary ultra-efficient aircraft propulsor 1020
(propulsor 1020) with a low augmentor fan ratio respectively, according
to two embodiments of the disclosure. FIGS. 10A and 10B show mass flow
streams that can be produced by the propulsors 1000 and 1020 at a high
and a low augmentor fan ratio (e.g., a ratio of thrust derived from an
augmentor fan to total engine thrust). The propulsors 1000 and 1020 each
have a structure that is similar to the ultra-efficient aircraft
propulsor 300, common features, functions, and elements will not be
redundantly described herein. The propulsor 1000 may comprise a core
engine 1002 and a ducted fan 1004 producing a combined core and ducted
fan flow 1008. The propulsor 1000 also comprises an augmentor fan 1006
producing an augmentor fan flow 1010. At a high ratio, a substantially
highest amount of thrust comes from the augmentor fan 1006, and at a low
ratio a substantially lower amount of thrust comes from the augmentor fan
1006.

[0097]The high augmentor fan ratio configuration of the propulsor 1000
causes the propulsor 1000 to produce the augmentor fan flow 1010 at about
60% to about 80% of total engine thrust, and a combined core and ducted
fan flow 1008 at about 20% to about 40% of total engine thrust. The
augmentor fan 1006 is configured to produce a substantially maximum
power. The power sharing drive system 312 may send most of the power to
the augmentor fan 1006, and a pitch angle of the augmentor fan 1006 may
be configured for a high angle of attack to substantially maximize the
power.

[0098]The augmentor fan 1006 has a higher thrust efficiency than the core
engine 1002 and the ducted fan 1004. This may be particularly true for
higher density air at lower altitudes. For example, the augmentor fan
1006 may be about 80% more efficient (i.e., has more thrust) than the
ducted fan 1004 at sea level, and about 50% more efficient at high
altitude. Thus, the augmentor fan 1006 is especially powerful for
takeoff.

[0100]The low augmentor fan ratio configuration of the propulsor 1020
causes the propulsor 1020 to produce the augmentor fan flow 1022 at about
40% of total engine thrust, and the combined core and the ducted fan flow
1008 at about 60% of total engine thrust. The augmentor fan 1006 is
configured to produce a substantially minimum level of noise. The power
sharing drive system 312 may send most of the power to the ducted fan
1004, and the pitch angle of the augmentor fan 1006 may be configured for
a low angle of attack to substantially minimize noise. Because of the low
augmentor fan ratio configuration of the augmentor fan 1006, the engine
can operate at a high power and rotation speed without excessive noise.
The ability to independently vary the power transferred to the ducted fan
1004 and the augmentor fan 1006 to produce variable levels of the ducted
fan flow 1008/1024 and the augmentor fan flow 1010/1022 respectively
provides the variable cycle engine capability as mentioned above.

[0102]The graph 1100 also illustrates a power sharing concept of the
ultra-efficient aircraft propulsor 300 according to one or more
embodiments of the disclosure. In practice, the power sharing can
optimize runway performance while reducing takeoff field length (TOFL) as
explained in more detail below. For a given takeoff placard thrust
rating, turbo props and propfans provide greater initial acceleration at
a very low speed but encounter rather rapid thrust lapse with forward
speed. In contrast, ducted turbofans have less initial acceleration but
greater available end-of-runway thrust. According to an embodiment of the
disclosure, takeoff field length can be substantially minimized by
changing the engine cycle, for example but without limitation, prior to
an airplane achieving decision speed (e.g., about midway through a
takeoff run). Accordingly, a low speed performance acceleration of the
augmentor fan 306 of the propulsor 300 is utilized, and then the
propulsor 300 is transitioned to a configuration utilizing the ducted fan
304 for the transition to lift off (e.g., at or near the end of the
runway) when some speed is accumulated as explained in more detail below.

[0103]In this manner, during takeoff the thrust ratio (propeller
thrust/total thrust) of the augmentor fan blades 308 of the augmentor fan
306 may be increased to greater than about 0.6 prior to transitioning to
the ducted fan 304 and decreased to less than 0.6 after transitioning to
the ducted fan 304, thereby optimizing the runway performance and
minimizing the TOFL respectively. Transition between the augmentor fan
306 and the ducted fan 304 may be accomplished by automatically changing
the pitch of the augmentor fan blades 308 in response to, for example but
without limitation, logic in the airplane flight management computer
systems. The logic may be based on flight parameters, such as but without
limitation, throttle input as explained above, airspeed, altitude, and
the like. As explained above, the ability to independently vary the power
transferred to the airflow between the ducted fan 304 and the augmentor
fan 306 provides the aforementioned variable cycle engine capability.

[0104]The ducted turbofan curve 1106 for the existing ducted turbofan
engine 100 (FIG. 1) shows the existing ducted turbofan engine 100 starts
with relatively low power up until, for example but without limitation,
about 40% of the runway length 1102. Thereafter, the existing ducted
turbofan engine 100 has a relatively high power. The existing ducted
turbofan engine 100 has a small rotor diameter, and may have a smaller
mass (smaller inertia) than the existing propfan engine 200 (FIG. 2) due
to smaller fan blades. As a result, the existing ducted turbofan engine
100 can increase its engine rotation rate (spin up) faster than the
existing propfan engine 200, and develops higher power later on the
runway. The existing ducted turbofan engine 100 may have the shortest
takeoff length to reach decision speed (V1). The decision speed V1 is an
important parameter in that it may be preferable for the engine to be in
a fixed configuration at the time the pilot commits to taking off. For
example, for combinations of airplane weight, and airport conditions
(e.g., wind-speed, temperature) where the optimum transition point
approaches V1, logic in the airplane Flight Management System (FMS) can
ensure that changes in the engine configuration are completed prior to
V1. In practice, the airplane runway speed data is included in the FMS
Thrust Ratio logic to allow for performing such an operation to
suitability monitor engine configuration of the propoulsor 300 prior to
V1.

[0105]The propfan curve 1108 for the open-rotor propfan engine 200 shows
the existing propfan engine 200 starts with relatively high power up
until, for example but without limitation, about 40% of the runway length
1102. Thereafter, the existing propfan engine 200 has relatively low
power. The existing propfan engine 200 generally has a large rotor
diameter, and may have a larger mass (higher inertia) than the existing
ducted turbofan engine 100 due to larger fan blades. As a result, the
existing propfan engine 200 has a relatively large rotating mass.
Therefore, the fan blades of the unducted propfan 204 of the existing
propfan engine 200 can be substantially feathered and the large rotating
mass can be spun-up to some degree before brake release 1112. After the
brake release 1112, rotational energy of the fan blades can be released
into the air flow driven by the unfeathered blades. Furthermore, the high
efficiency of the existing propfan engine 200 is most effective at low
speeds. As a result, the existing propfan engine 200 has a fast early
acceleration 1114, but slower acceleration farther down the runway.

[0106]The augmentor fan curve 1110 shows the augmentor fan 306, according
to an embodiment of the disclosure, by itself may have slightly less low
speed performance than the existing propfan engine 200, but may have
slightly better high speed performance. However, according to an
embodiment of the disclosure, the ultra-efficient aircraft propulsor 300
also comprises the ducted fan 304. Thus, the ultra-efficient aircraft
propulsor 300 may use higher thrust from the augmentor fan 306 above up
to, for example but without limitation, about 40% of the runway length
1102, and the ducted fan 304 above, for example without limitation, about
40% of the runway length 1102. Thus, the ultra-efficient aircraft
propulsor 300 can use a superior characteristic of both the augmentor fan
306 and the ducted fan 304 to enhance takeoff performance. The
ultra-efficient aircraft propulsor 300 may reduce the takeoff length to
reach V1 by an amount (d) compared to the existing propfan engine 200. By
using the ducted fan 304 and the lower noise configuration of the
augmentor fan blades 308 for the augmentor fan 306 at substantially
during takeoff, noise is also reduced. The ability to tailor power split
between the ducted fan 304 and the augmentor fan 306 can be, for example
but without limitation, optimized for different airports and takeoff
scenarios as a function of groundspeed, airspeed, main and/or nose gear
on ground sensor signals, flap positions, aircraft weight, airspeed,
altitude, dynamic pressure, radio altitude, proximity to flyover and/or
sideline and/or airport-specific microphone locations and the like, to
optimize field performance and noise.

[0107]FIG. 12 is a graph showing flight Mach number (M) vs. variable
augmentor fan thrust ratio for an exemplary flight envelope according to
an embodiment of the disclosure. As explained above in the context of
discussion of FIG. 11, during takeoff, an about 60% augmentor fan 306
thrust ratio may be used to enhance low speed takeoff acceleration, and
reduced to about 40% of takeoff roll to enhance turbofan power and reduce
noise. During climb in to a cruise flight segment over populated areas, a
low noise profile is maintained, and as altitude increases, the power can
be shifted to the higher efficiency high augmentor ratio (high augmentor
fan thrust ratio). For example, at M equal to about 0.35, during the
climb, the propulsor 300 uses an augmentor fan thrust ratio of about 40%
and at M equal to about 0.8, during cruise, the propulsor 300 is
backed-off to using about 60% augmentor fan thrust ratio again.

[0108]An additional capability provided by various embodiments of the
disclosure entails the ability to tailor thrust ratio to specific airport
noise monitoring systems. Specifically, certain airports such as Santa
Ana (SNA), Brussels (BRU), Osaka (OSA), Munich (MUC) have numerous
microphones placed in noise sensitive residential areas, each of which
have stated substantially maximum noise levels as defined by the airport.
Existing airplanes may have to alter their flight path and or rapidly
modulate thrust to avoid exceeding stated noise limits which can increase
pilot workload and can reduce passenger ride-comfort due to almost a
sudden change in airplane attitude.

[0109]Future Flight Management Systems (FMS) systems may comprise
databases of microphone locations to assist pilots with precise automatic
throttle operation; however, the exemplary embodiments can utilize logic
in the FMS that also comprises predefined optimum thrust ratio control
logic so that noise can be tailored with less change in actual thrust
produced resulting in less pilot workload and improved passenger comfort.
During decent, the aircraft is mostly gliding; however, for safety the
aircraft needs to have power readily available. Because the augmentor fan
306 can substantially feather its props to reduce thrust while
maintaining rotational momentum, it can provide quick power simply by
changing an angle of one or more of the augmentor fan blades 308. In this
manner, the ultra-efficient aircraft propulsor 300 enhances safety.

[0110]Certain noise sensitive airports also encourage steep descents to
substantially minimize noise. While a typical glide slope is about three
degrees, angles as high as about six degrees are standard approach vector
by certain airports including London City (LCY). Airplane wing design
largely controls these angles, however, a factor that can limit descent
angle is a rate at which engines can "spool up" or achieve usable thrust
in an emergency. Embodiments of the disclosure, enables an engine such as
the propulser 300 to achieve a usable thrust faster than the ducted
turbofan engine 100. In this manner, embodiments of the disclosure can
enable an aircraft to achieve steeper and/or quieter descents into
noise-sensitive airports.

[0111]FIG. 13 is an illustration of an exemplary natural laminar flow on
an engine nacelle 1302 for a conventional turbofan. The engine nacelle
1302 on the conventional turbofan is generally designed to be naturally
laminar for cruise speeds. However, at lower speeds and flight attitudes,
front portions of the engine nacelle 1302 have a laminar boundary layer
1304, but other parts of the engine nacelle 1302 may not. At lower
speeds, the laminar boundary layer 1304 transitions 1306 into a turbulent
boundary layer 1308.

[0112]FIG. 14 is an illustration of an exemplary extended natural laminar
flow 1408 on an engine nacelle of an exemplary ultra-efficient aircraft
propulsor with an augmentor fan 1406 according to an embodiment of the
disclosure. Because the augmentor fan 1406 accelerates, the air around
the nacelle to a high speed, the boundary layer is energized, thereby
laminarizing the flow over a greater region of the trailing nacelle
portion 1404 as well as the leading nacelle portion 1402, thereby
reducing drag.

[0113]FIG. 15 is an illustration of a rear view of an agumentor fan 1500
showing an augmentor fan tip ring 1502 (tip ring) according to an
embodiment of the disclosure. The augmentor fan tip ring 1502
circumscribes the augmentor fan 1504 and blades thereof. The augmentor
fan tip ring 1502 may also circumscribe a ducted fan 1508 and/or a core
engine 1510. The augmentor fan tip ring 1502 reduces or eliminates blade
tip vortices. Reducing or eliminating blade tip vortexes can reduce drag
and noise. The augmentor fan tip ring 1502 can also provide a containment
to ensure that damaged blades do not fly loose, which may also offer an
improvement in passenger perception and preference. In practice, the
augmentor fan tip ring 1502 may have a slightly noncircular shape when
the augmentor fan 1504 is not rotating. When the augmentor fan 1504 is
rotating, the rotational loads, cause the augmentor fan tip ring 1502 to
take a circular or near-circular shape at typical operational rotation
speeds. An average chord of the augmentor fan tip ring 1502 may be, for
example and without limitation, between about 0.025 and about 0.5 of an
average chord of the fan cowl 1506. The augmentor fan tip ring 1502 may
comprise, for example but without limitation, a ring airfoil
configuration, where an average chord of the ring airfoil may be, for
example and without limitation, between 1 and 5 times the average chord
of blades of the augmentor fan 1504. The average thickness to average
chord ratio of the ring airfoil may be, for example but limitation,
between about 0.03 and about 0.30. The augmentor fan 1504 may have blade
pitch variability operable to allow coupling of augmentor fan blades to
the augmentor fan tip ring 1502.

[0114]FIG. 16 is an illustration of an exemplary shark fin blade 1608
according to an embodiment of the disclosure in comparison to a
conventional scimitar blade 1602. The conventional scimitar blade 1602
comprises a narrow root chord 1606 due to a requirement to attach to a
conventional propfan hub/spinner 1604. In contrast, according to an
embodiment of the disclosure, a larger width of the augmentor hub ring
408 (FIG. 4) allows a more trapezoidal (shark fin) shape planform 1610
that has greater lift at the root 1616. In this manner, the root chord
1612 of the shark fin blade 1608 can be much wider than the width of the
narrow root chord 1606 of the conventional scimitar blade 1602. The shark
fin blade 1608 can utilize an end-plating effect (root loading) to
provide high lift at the root 1616. The root 1616 is inherently stronger
than would be possible for the conventional propfan hub/spinner 1604
since it can be bonded to an augment hub ring portion 1636. In this
manner, the augmentor fan blades 406 (FIG. 4) can have airfoil acoustic
shaping features.

[0115]Aerodynamic tip-sweep 1634 of a mid chord line 1626 relative to a
plane perpendicular to a local inflow streamlines 1630 can be up to about
60 degrees or more. For current art, aero tip-sweep 1632 of a mid chord
line 1624 relative to a plane perpendicular to a local inflow streamlines
1628 can be generally not more than about 40-45 degrees.

[0116]FIG. 17 is an illustration of an exemplary augmentor fan blade pitch
control unit (PCU) mechanism 1700 according to an embodiment of the
disclosure. A rotating gear ring 1706 provides torque to all the
augmentor fan blade roots 1702 simultaneously from all the PCU drives
1704 for pitch control. The augmentor fan blade roots 1702 may be paired
with PCU drives 1704 coupled to the rotating gear ring 1706. Thereby, if
one or more of the PCU drives 1704 fails; the remaining PCU drives 1704
can still drive all the augmentor fan blades 1708. In this manner, a
number of PCU drives 1704 can significantly be reduced. The rotating gear
ring 1706 is operable to ensure same pitch angle for all the augmentor
fan blades 1708; therefore, no counter weight may be needed. The rotating
gear ring 1706 may be, for example but without limitation, automatically
driven electrically, hydraulically, pneumatically, a combination thereof,
and the like. The PCU drives 1704 can be controlled automatically via a
flight management system in response to data from an engine control unit
ECU and the like.

[0117]FIG. 18 is an illustration of a front view of an exemplary rotating
gear ring 1706 of an augmentor fan blade pitch control unit (PCU)
according to an embodiment of the disclosure. The rotating gear ring 1706
comprises augmentor fan blade roots 1702 paired with control gears 1704
(PCU drives 1704) and coupled to the rotating gear ring 1706.

[0118]FIG. 19 is an illustration of an exemplary block diagram for a power
sharing drive system 1900 operable to use for power sharing control of
the propulsor 300 according to an embodiment of the disclosure. The power
sharing drive system 1900 comprises an augmentor fan 1902, a power
splitter 1904, a turbofan 1906, a core engine 1908, and a controller
1910. The power sharing drive system 1900 has a structure that is similar
to the ultra-efficient aircraft propulsor 300, common features,
functions, and elements will not be redundantly described herein. The
power sharing drive system 1900 may comprise gears or other systems
operable to transmit power concurrent with changing revolutions per
minute.

[0119]The power splitter 1904 is operable to receive power from the core
engine 1908 (e.g., in the form of torque), and transmit the power to the
augmentor fan 1902 and/or the turbofan 1906. The power splitter 1904
splits the power between the augmentor fan 1902 and/or the turbofan 1906
as directed by the controller 1910. The controller 1910 may set the power
split based on flight parameters such as, for example but without
limitation, speed (e.g., Mach number), dynamic pressure, altitude,
weight, flap configuration, landing gear parameters, takeoff status,
landing status, approach status, cruise status, and the like. The flight
parameters may be obtained from, for example but without limitation, the
flight control system or sensors of the aircraft. The power splitter 1904
may comprise, for example but without limitation, a gear system (FIG.
21), a hydraulic system, separate turbine stages (e.g., spools) for the
turbofan and the augmentor fan, and the like. The power splitter 1904 may
be used to vary respective RPM and/or relative RPM of the augmentor fan
1902 and/or the turbofan 1906.

[0120]The controller 1910 is configured to control, for example but
without limitation, at least one of core engine power, core engine
thrust, core engine RPM, core engine fuel flow, core engine critical
temperature parameter, fan thrust, fan RPM, augmentor fan blade pitches,
augmentor fan thrust, augmentor fan RPM, and the like. The controller
1910 is further configured to control at least a fraction of propulsor
300 total mass flow which is run through the augmentor fan 1902, and a
fraction of propulsor total power which is run through the turbofan 1906.
The power sharing control allows optimization for minimum fuel burn,
minimum operational cost, minimum emissions and/or minimum noise.

[0121]FIG. 20A is an illustration of an exemplary ultra-efficient aircraft
propulsor 2000 using a power sharing drive system 2004 (power splitter
2004) according to an embodiment of the disclosure. FIG. 20B is an
illustration of a cut-away perspective view of the exemplary
ultra-efficient aircraft propulsor 2000 using the power sharing drive
system 2004. The ultra-efficient aircraft propulsor 2000 has a structure
that is similar to the ultra-efficient aircraft propulsor 300 and power
sharing drive system 1900, common features, functions, and elements will
not be redundantly described herein.

[0122]The ultra-efficient aircraft propulsor 2000 comprises an augmentor
fan 2002, a power splitter 2004, a turbofan 2006 (ducted fan 2006), a
core engine 2008, and a controller 2010. The power splitter 2004 may be,
for example but without limitation, a differential gearbox drive system
as explained below.

[0123]FIG. 21 is an illustration of an exemplary differential gearbox
drive system 2100 that can be used as the power splitter 2004 according
to an embodiment of the disclosure. The differential gearbox drive system
2100 has a structure that is similar to the power splitter 1904 in FIG.
19, common features, functions, and elements will not be redundantly
described herein. The differential gearbox drive system 2100 comprises an
output 2102 to turbofan 2006 (FIGS. 20A/20B), a power input shaft 2104
coupled to the core engine 2008 (FIGS. 20A/20B), a plurality of
differential spider gears 2106, a power transfer ring 2108, a stationary
cowl and propulsion support 2110, a plurality of planetary power transfer
gears 2112, and an augmentor output 2114 to the augmentor fan 2002 (FIGS.
20A/20B). In practice, the differential gearbox drive system 2100 is
operable to receive power from the core engine 2008 (e.g., in the form of
torque) via, for example, the power input shaft 2104, and transmit the
power to the augmentor fan 2002 and/or the turbofan 2006 via the
augmentor output 2114, and the output 2102 respectively. The differential
gearbox drive system 2100 is configured to suitably split the power
between the augmentor fan 2002 and/or the turbofan 2006 as directed by
the controller 2010 (FIGS. 20A/20B). In response to input from the
controller 2010, the differential gearbox drive system 2100 provides a
suitable gearing mechanism via the differential spider gears 2106 and the
planetary power transfer gears 2112 to carry operation of the
ultra-efficient aircraft propulsor 300 (FIG. 3).

[0124]FIGS. 22-25 are illustrations of various embodiments of exemplary
ultra-efficient aircraft propulsors according to the present disclosure.
Embodiments shown in FIGS. 22-25 comprise a structure that is similar to
the ultra-efficient aircraft propulsor 300 and the power sharing drive
system 1900, common features, functions, and elements will not be
redundantly described herein.

[0125]FIG. 22 is an illustration of an exemplary ultra-efficient aircraft
propulsor 2200 showing a single rotor tractor configuration using a power
sharing drive system according to an embodiment of the disclosure. The
ultra-efficient aircraft propulsor 2200 comprises an augmentor fan 2202,
a power splitter 2204, a turbofan 2206, and a core engine 2208. In the
embodiment shown in FIG. 22, a power sharing differential gearbox drive
system such as the power splitter 2204 is used for power sharing control.
The power splitter 2204 comprises a puller or tractor configuration.

[0126]FIG. 23 is an illustration of an exemplary ultra-efficient aircraft
propulsor 2300 showing a single rotor pusher configuration using a power
sharing drive system according to an embodiment of the disclosure. The
ultra-efficient aircraft propulsor 2300 comprises an augmentor fan 2302,
the power splitter 2304, a turbofan 2306, and a core engine 2308. In the
embodiment shown in FIG. 23, an exemplary power sharing differential
gearbox drive system such as the power splitter 2304 is used for power
sharing control.

[0127]FIG. 24 is an illustration of an exemplary ultra-efficient aircraft
propulsor 2400 (propulsor 2400) showing a single rotor tractor
configuration with an augmentor fan 2402 located forward of a turbofan
2406 using a power sharing differential gearbox drive system 2404 (power
splitter 2404) driven by a core engine 2408 according to an embodiment of
the disclosure. The power sharing differential gearbox drive system 2404
comprises a puller configuration. Since the augmentor fan 2402 is located
forward of the turbofan 2406, a front portion 2410 of the propulsor 2400
(e.g., a front portion of a fan cowl) may be designed to rotate with the
augmentor fan 2402.

[0128]FIG. 25 is an illustration of an exemplary ultra-efficient aircraft
propulsor 2500 (propulsor 2500) showing a single rotor pusher
configuration with a forward turbofan puller configuration using a power
sharing drive system according to an embodiment of the disclosure. The
ultra-efficient aircraft propulsor 2500 comprises an augmentor fan 2502,
a power splitter 2504, a turbofan 2506, and a core engine 2508. In the
embodiment shown in FIG. 25, an exemplary power sharing differential
gearbox drive system such as the power splitter 2504 is used for power
sharing control. The propulsor 2500 comprises a puller turbofan 2506
configuration and a pusher augmentor fan 2502 configuration driven by the
power splitter 2504.

[0129]FIG. 26A illustrates a perspective view of an exemplary
ultra-efficient aircraft propulsor 2600 using a powered augmentor fan hub
rotor according to an embodiment of the disclosure. The ultra-efficient
aircraft propulsor 2600 comprises a core engine 2602, a ducted fan 2604,
an augmentor hub ring 2606, and a plurality of augmentor fan blades 2608.
As shown in FIG. 26, the augmentor hub ring 2606 may, without limitation,
surround and shroud a ducted fan 2604.

[0130]As shown in FIG. 26, roots (1616 in FIG. 16) of each of the
augmentor fan blades 2608 are coupled to the augmentor hub ring 2606,
which may be, without limitation, substantially coplanar with the fan
cowl 2618. The augmentor hub ring 2606 is configured to rotate. The
augmentor hub ring 2606 comprises blade pitch variability permitting
coupling of the augmentor fan blades 2608. In one embodiment, the
augmentor hub ring 2606 is substantially located on an outer circle of
larger size and surrounding the outer perimeter of the fan cowl 2618.

[0131]The augmentor hub ring 2606 comprises a driven gear ring 2620 around
a periphery of the augmentor hub ring 2606 and coupled to connecting gear
elements 2614 that transmit power from at least one driving gear ring
2612. The at least one driving gear ring 2612 may be coupled to and
rotationally driven by power from the core engine 2602 and/or the ducted
fan 2604. The connecting gear elements 2614 are contained in a plurality
of struts 2616 to improve aero dynamics and protect the connecting gear
elements 2614. The augmentor hub ring 2606 may be driven by the same
number of struts 2616 as the number of the augmentor fan blades 2608, or
may use a smaller or larger number of struts 2616 to directly or
indirectly drive a rotation of the augmentor hub ring 2606. Gear
sprockets 2610 of the connecting gear elements 2614 each may comprise a
driving differential gear for transmitting power from one or more power
shafts from the core engine 2602, while concurrently changing revolutions
per minute.

[0132]The number of struts 2616 (i.e., 5 struts) is smaller than the
number of the augmentor fan blades 2608 (i.e., 10 blades); the small
number of struts 2616 minimizes disruption of the air flow of the ducted
fan 2604. The arrangement of ultra-efficient aircraft propulsor 2600 with
a large diameter augmentor fan hub or ring allows the number of the
augmentor fan blades 2608 to be large, which minimizes noise as explained
above. The augmentor hub ring 2606 may be structurally coupled to the fan
cowl 2618.

[0133]FIG. 26B is an illustration of a schematic cross sectional view of a
portion of an exemplary ultra-efficient aircraft propulsor using a
powered augmentor hub rotor driven by a turbofan according to an
embodiment of the disclosure. For the embodiment shown in FIG. 2B, an
augmentor fan tip ring 2628 is coupled to the augmentor fan blades 2608,
and is rotationally driven using power from the ducted fan 2604. A first
gear sprocket 2626 is engaged by a driving gear ring 2632 of the turbofan
2604. A shaft 2624 couples the first gear sprocket 2626 and a second gear
sprocket 2622. The second gear sprocket 2622 engages a driven gear ring
2630 on the augmentor hub tip ring 2628. A circumference of the second
gear sprocket 2622 may be less than a circumference of the first gear
sprocket 2626, to cause an effective gearing where the rotational RPM of
the driven gear ring 2632 can be reduced relative to the rotational RPM
of the driving gear ring 2632.

[0134]FIG. 27 is an illustration of an exemplary dual pusher configuration
of an ultra-efficient aircraft propulsor 2700 (propulsor 2700) utilizing
a lobed mixer to provide cooled flow to aerodynamically drive an
augmentor fan according to an embodiment of the disclosure. The propulsor
2700 has a structure that is similar to the ultra-efficient aircraft
propulsor 300, common features, functions, and elements will not be
redundantly described herein. The propulsor 2700 comprises a lobed mixer
2706, contra-rotating augmentor fans 2708 and 2710, and power sharing
drive system 2714. The propulsor 2700 uses no gear to drive the
contra-rotating augmenter fans 2708 and 2710. The lobed mixer 2706 mixes
the cold turbofan air 2704 with a hot core engine exhaust 2702 to produce
a cooled mixed flow 2712 which can directly drive the contra-rotating
augmentor fans 2708 and 2710 (power turbine). The cooled mixed flow 2712
contrasts with pervious existing art that used the hot core engine
exhaust 2702 to directly drive propfans. The lower temperature reduces
demand for auxiliary cooling systems (e.g., cooling turbine vanes) and
allows use of less high temperature resistant materials, lowering cost,
reducing noise, reducing maintenance, and enhancing performance. In this
manner, cooled gasses from the lobed mixer 2706 reduces temperature
related wear on, for example but without limitation, the contra-rotating
augmenter fans 2708 and 2710 and pitch control unit (PCU) drives 1704 of
the contra-rotating augmenter fans 2708 and 2710. The power sharing drive
system 2714 may comprise variable vanes 2716 and 2718 operable to change
configuration to vary power to the contra-rotating augmentor fans 2708
and 2710 respectively. As shown in FIG. 27, mounting the propulsor 2700
at an aft end of an engine in a pusher configuration allows for a smaller
overall propulsor diameter of the contra-rotating augmentor fans 2708 and
2710 since propulsor diameter is then not dependent on a size of a
turbofan. Configuration of the propulsor 2700 allows mounting the engine,
for example but without limitation, under wings of an aircraft.

[0135]FIG. 28 is an illustration of a perspective view of an exemplary
under wing mounting of a contra-rotating dual pusher configuration of an
ultra-efficient aircraft propulsor (propulsor 2804) with an augmentor fan
according to an embodiment of the disclosure. As shown in FIG. 28, the
propulsor 2804 comprising augmentor fans 2802 is mounted under a wing
2806 of a high wing aircraft 2808.

[0136]FIG. 29 is an illustration of top and side views of an exemplary
tail mounting of a contra-rotating dual rotor pusher configuration of an
ultra-efficient aircraft propulsor 2902 (propulsor 2902) with an
augmentor fan according to an embodiment of the disclosure. As shown in
FIG. 29, two exemplary propulsors 2902 are mounted on a tail section of a
low wing aircraft 2904.

[0137]FIG. 30 is an illustration of top, side, and front views of an
exemplary tail mounting of a single rotor tractor configuration of the
ultra-efficient aircraft propulsor 3002 (propulsor 3002) with an
augmentor fan according to an embodiment of the disclosure. As shown in
FIG. 30, two propulsors 3002 are mounted on a tail section of a low wing
aircraft 3004.

[0138]FIG. 31 is an illustration of top and side views of an exemplary
tail mounting of a single rotor pusher configuration of an
ultra-efficient aircraft propulsor 3102 (propulsor 3102) with an
augmentor fan according to an embodiment of the disclosure. As shown in
FIG. 31, two propulsors 3102 are mounted on a tail section of a low wing
aircraft 3104.

[0139]FIG. 32 is an illustration of top, side, and front views an
exemplary under wing mounting on a large mid-wing aircraft 3204 of a
single rotor tractor configuration of the ultra-efficient aircraft
propulsor 3202 (propulsor 3202) with an augmentor fan according to an
embodiment of the disclosure. As shown in FIG. 32, two exemplary
ultra-efficient aircraft propulsors 3202 are mounted on respective wings
of a mid-wing aircraft 3204.

[0140]FIG. 33 is an illustration of side, top and front views of an
exemplary low-wing mounting of a single rotor tractor ultra-efficient
aircraft propulsor 3304 (propulsor 3304) showing an encircling spinning
tip ring 3304 (i.e., similar to augmentor fan tip ring 1502) according to
an embodiment of the disclosure. The encircling spinning tip ring 3304
can provide the ultra-efficient aircraft propulsor 300 with further noise
reduction. As shown in FIG. 33, two propulsors 3308 each comprising an
encircling spinning tip ring 3304 are mounted on respective wings 3306 of
a low-wing aircraft 3302.

[0141]FIGS. 34-38 are illustrations of various embodiments of
ultra-efficient aircraft propulsors according the present disclosure.
Embodiments shown in FIGS. 34-38 may have functions, material, and
structures that are similar to the embodiments shown in FIGS. 3-33.
Therefore common features, functions, and elements may not be redundantly
described here.

[0142]FIG. 34 is an illustration of a schematic cross sectional view of an
exemplary thrust reverser configuration of an ultra-efficient aircraft
propulsor 3400 with an augmentor fan 3406 according to an embodiment of
the disclosure. The thrust reverser 3416 is configured to produce reverse
thrust by reversing the ducted fan mass flow steam 804 (FIG. 8) from the
ducted fan 3404. As shown in the embodiment of FIG. 34, a standard type
of thrust reverser can be fitted to a ducted fan 3404 of an
ultra-efficient aircraft propulsor such as ultra-efficient aircraft
propulsor 3400. Alternatively, a thrust reverser can be fitted to a core
engine 3402 to reverse the core mass flow stream 802 (FIG. 8). In some
embodiments, a thrust reverse can be fitted to an augmentor fan blade
3410 with or without a tip ring (encircling spinning tip ring 3304 in
FIG. 33). The thrust reverser 3416 may be any of the thrust reverser
types 3912 explained below in the context of discussion of FIG. 39. As
explained below, the thrust reverser 3416 may also comprise means for
changing the pitch orientation of the augmentor fan blades 3410. In one
embodiment, a flow vectoring device such as the flow vectoring device
3926 (FIG. 39) may be used for vectoring the flow downstream of at least
one of the core engine 3402, the ducted fan 3404, and/or the augmentor
fan 3406. A drive system 3408 comprises a gear architecture of the drive
system 2612 of FIG. 26 mounted on an aft end of fan cowl 3414. A gear
sprocket 3412 drives the augmentor fan blades 3410.

[0143]FIG. 35 is an illustration of a schematic cross sectional view of an
exemplary ultra-efficient aircraft propulsor 3500 (propulsor 3500) with a
front mounted augmentor fan and thrust reverser configuration according
to an embodiment of the disclosure. The propulsor 3500 comprises a core
engine 3502, a ducted fan 3504, an augmentor fan 3506, and a thrust
reverser 3516. The augmentor fan 3506 utilizes the gear architecture of
the drive system 2612 of FIG. 26 (drive system 3508) mounted on a forward
end of the fan cowl 3514. An augmentor hub ring 3512 rotates the
augmentor fan blades 3510 on the forward end of the fan cowl 3514. The
thrust reverser 3516 comprises similar functionality as the thrust
reversers 3416 (FIG. 34), but is shown in a non-deployed position.

[0144]FIG. 36 is an illustration of a schematic cross sectional view of an
exemplary ultra-efficient aircraft propulsor 3600 (propulsor 3600) with a
front mounted augmentor fan according to an embodiment of the disclosure.
The propulsor 3600 comprises a core engine 3602, a ducted fan 3604, and
an augmentor fan 3606. The augmentor fan 3606 utilizes a drive system
3608 mounted on a forward end of the fan cowl 3614. An augmentor hub ring
3612 rotates the augmentor fan blades 3610 on the forward end of the fan
cowl 3614.

[0145]FIG. 37 is an illustration of a schematic cross sectional view of an
exemplary dual puller configuration of an ultra-efficient aircraft
propulsor 3700 (puller configuration 3700) with an augmentor fan
according to an embodiment of the disclosure. The puller configuration
3700 comprises a core engine 3702, a ducted fan 3704, a first augmentor
fan 3706, and a second augmentor fan 3716. The first augmentor fan 3706
is mounted on a forward end of the fan cowl 3714. An augmentor hub ring
3712 rotates first augmentor fan blades 3710 on the forward end of the
fan cowl 3714. The second augmentor fan 3716 is mounted on an aft end of
the fan cowl 3714. An augmentor hub ring 3718 rotates second augmentor
fan blades 3720 on the aft end of the fan cowl 3714. A drive system 3708
provides power splitting between the core engine 3702, the ducted fan
3704, the first augmentor fan 3706, and the second augmentor fan 3716. In
some embodiments, the first augmentor fan blades 3710 and the second
augmentor fan blades 3720 are configured to rotate in the same direction.
Alternately, the first augmentor fan blades 3710 and the second augmentor
fan blades 3720 can be configured to contra-rotate with respect to one
another. The puller configuration 3700 allows a doubling of the number of
total augmentor fan blades, which can be used to reduce blade loading,
hub-to-tip ratio, and wavedrag.

[0146]FIG. 38 is an illustration of a schematic cross sectional view of an
exemplary dual puller configuration of an ultra-efficient aircraft
propulsor 3800 (puller configuration 3800) with two augmentor fans
according to an embodiment of the disclosure. The propulsor 3800
comprises a core engine 3802, a ducted fan 3804, a first augmentor fan
3806, and a second augmentor fan 3816, a first augmentor hub ring 3812,
and a second augmentor hub ring 3818. The second augmentor hub ring 3818
substantially surrounds an inner perimeter of the fan cowl 3814 and is
longitudinally spaced from the first augmentor hub ring 3812. The second
augmentor hub ring 3818 may be operable to contra-rotate relative to the
first augmentor hub ring 3812. The first augmentor hub ring 3812 and the
second augmentor hub ring 3818 are driven by the core engine 3802. The
first augmentor hub ring 3812 comprises a plurality of first augmentor
fan blades 3810 arranged circumferentially around the first augmentor hub
ring 3812. The second augmentor hub ring 3818 comprises a plurality of
second augmentor fan blades 3820 arranged circumferentially around the
second augmentor hub ring 3818. A number of the first augmentor fan
blades 3810 and/or a number of the second augmentor fan blades 3820 can
be chosen to avoid sum and difference tones.

[0147]A drive system 3808 provides power splitting between the core engine
3802, the ducted fan 3804, the first augmentor fan 3806, and the second
augmentor fan 3816. In some embodiments, the first augmentor fan blades
3810 and the second augmentor fan blades 3820 are configured to rotate in
the same direction. Alternately, the first augmentor fan blades 3810 and
the second augmentor fan blades 3820 can be configured to contra-rotate
with respect to one another. The drive system 3808 utilizes the gear
architecture of the drive system 2612 of FIG. 26.

[0148]By using two or more augmentor fans, the ultra-efficient aircraft
propulsor 3800 provides a large total number of blades and the noise and
wave drag benefits thereof. For example but without limitation, if there
are 17 first augmentor fan blades 3810 and 15 second augmentor fan blades
3820, that is approximately equivalent to a single augmentor fan with 32
blades. The BPF can be calculated as shown above in the context of FIG. 6
at 2400 rpm as 1280 Hz, with the improved noise characteristics thereof.
The puller configuration 3800 allows a doubling of the number of total
blades, which can be used to reduce blade loading, hub-to-tip ratio, and
wavedrag.

[0149]FIG. 39 is an illustration of an exemplary block diagram 3900 of an
ultra-efficient aircraft propulsor engine according to various
embodiments of the disclosure. The block diagram 3900 is a generalization
of the embodiments shown in FIGS. 3-38. The block diagram 3900 may have
functions, material, and structures that are similar to the embodiments
shown in FIGS. 3-38. Therefore common features, functions, and elements
may not be redundantly described here. The block diagram 3900 comprises:
a core engine 3902, a ducted fan 3904, an augmentor fan 3906, drive means
3908, and thrust reverser means 3910.

[0150]The core engine 3902 is operable to drive the augmentor fan 3906.
The core engine 3902 substantially utilizes at least one of the
thermodynamic cycles mentioned above in the context of discussion of FIG.
3. The core engine 3902 architecture may be, for example but without
limitation, at least one of a 1-spool 3928, 2-spool 3930, 3-spool 3932,
4-spool 3934, and the like.

[0151]The ducted fan 3904 is operable to be driven by the core engine
3902. The ducted fan 3904 comprises fan blades 3936 circumferentially
contained by a fan cowl (duct) 3938 as explained in the context of
discussion of FIG. 3 above.

[0153]The drive means 3908 may comprise gear means 3950 for transmitting
power while changing revolutions per minute. The gear means 3950
comprises a driving gear ring 3952 around an inner perimeter of the fan
cowl 3938, a driven gear ring 3954 around an inner periphery of the
augmentor hub ring 3940, and connecting gear elements 3956 provided
between a driving gear ring 3952 and the driven gear ring 3954.

[0154]The connecting gear elements 2614/3956 comprise a first gear
sprocket 3958 engaged by the driving gear ring 2610/3952, a second gear
sprocket 3960 engaging the driven gear ring 3954 on the augmentor hub
ring 2606/3940, and a shaft (not shown) connecting hubs of the first gear
sprocket 3958 and the second gear sprocket 3960. The circumference of the
second gear sprocket 3960 is less than the circumference of the first
gear sprocket 3958, to cause an effective gearing wherein the rotational
RPM of the driven gear ring 3954 is reduced relative to the rotational
RPM of the driving gear ring 2610/3952.

[0155]The thrust reverser means 3910 is operable to reverse at least one
of the core mass flow stream 802 and the ducted fan mass flow stream 804,
and the augmentor fan mass flow stream 806. The thrust reverse means 3910
may comprise a variety of thrust reverser types 3912, for example but
without limitation, petal reverser elements 3914, cascade reverser
elements 3916, blocker door reverser elements 3918, clamshell reverser
elements 3920, target reverser elements 3922, flow deflecting vane
reverser elements 3924, and the like. In one embodiment, a flow vectoring
device 3926 may be used for vectoring the flow downstream of at least one
of the core engine 3902, the ducted fan 3904, and/or the augmentor fan
3906. The thrust reverser means 3910 may also comprise, for example but
without limitation, means for changing a pitch orientation of the
augmentor fan blades 3934, and the like.

[0156]Although exemplary embodiments of the present disclosure have been
described above with reference to the accompanying drawings, it is
understood that the disclosure is not limited to the above-described
embodiments. Various alterations and modifications to the above
embodiments are contemplated to be within the scope of the disclosure. It
should be understood that those alterations and modifications are
included in the technical scope of the disclosure as defined by the
appended claims.

[0157]While at least one exemplary embodiment has been presented in the
foregoing detailed description, the present disclosure is not limited to
the above-described embodiment or embodiments. Variations may be apparent
to those skilled in the art. In carrying out the present disclosure,
various modifications, combinations, sub-combinations and alterations may
occur in regard to the elements of the above-described embodiment insofar
as they are within the technical scope of the present disclosure or the
equivalents thereof. The exemplary embodiment or exemplary embodiments
are examples, and are not intended to limit the scope, applicability, or
configuration of the disclosure in any way. Rather, the foregoing
detailed description will provide those skilled in the art with a
template for implementing the exemplary embodiment or exemplary
embodiments. It should be understood that various changes can be made in
the function and arrangement of elements without departing from the scope
of the disclosure as set forth in the appended claims and the legal
equivalents thereof. Furthermore, although embodiments of the present
disclosure have been described with reference to the accompanying
drawings, it is to be noted that changes and modifications may be
apparent to those skilled in the art. Such changes and modifications are
to be understood as being included within the scope of the present
disclosure as defined by the claims.

[0158]Terms and phrases used in this document, and variations hereof,
unless otherwise expressly stated, should be construed as open ended as
opposed to limiting. As examples of the foregoing: the term "including"
should be read as mean "including, without limitation" or the like; the
term "example" is used to provide exemplary instances of the item in
discussion, not an exhaustive or limiting list thereof; and adjectives
such as "conventional," "traditional," "normal," "standard," "known" and
terms of similar meaning should not be construed as limiting the item
described to a given time period or to an item available as of a given
time, but instead should be read to encompass conventional, traditional,
normal, or standard technologies that may be available or known now or at
any time in the future. Likewise, a group of items linked with the
conjunction "and" should not be read as requiring that each and every one
of those items be present in the grouping, but rather should be read as
"and/or" unless expressly stated otherwise. Similarly, a group of items
linked with the conjunction "or" should not be read as requiring mutual
exclusivity among that group, but rather should also be read as "and/or"
unless expressly stated otherwise. Furthermore, although items, elements
or components of the disclosure may be described or claimed in the
singular, the plural is contemplated to be within the scope thereof
unless limitation to the singular is explicitly stated. The presence of
broadening words and phrases such as "one or more," "at least," "but not
limited to" or other like phrases in some instances shall not be read to
mean that the narrower case is intended or required in instances where
such broadening phrases may be absent. The term "about" when referring to
a numerical value or range is intended to encompass values resulting from
experimental error that can occur when taking measurements.